An LED device generally includes an LED bracket, an LED chip and an encapsulation colloid. The LED bracket includes a metal bracket and a cup cover wrapping the metal bracket. When the LED device is working, a PN junction of the LED chip is energized and conducted, and the LED chip converts electric energy into light energy to emit light rays. The LED bracket, the LED chip or the encapsulation colloid may influence a light emitting effect or display effect of an LED product.
For example, a contrast ratio, as an important index for measuring the display effect of the LED product, may generate an important influence on the display effect and a visual effect of human eyes. Generally speaking, the larger the contrast ratio is, the more clear and striking images are and the more bright and beautiful colors are. If the contrast ratio is smaller, an entire display picture formed by the LED may present a dusky phenomenon, thereby seriously affecting an appreciation effect on the human eyes.